Process for making a synthesis gas by reforming of a hydrocarbon and including recovery of carbon dioxide at high temperature

Abstract

Process for making a hydrogen-containing synthesis gas (105) from a hydrocarbon feedstock (101), comprising the reforming of said hydrocarbon feedstock and purification of raw synthesis gas, said purification comprising shift conversion of carbon monoxide into carbon dioxide and subsequent absorption of carbon dioxide into an absorbing medium (7a, 14), resulting in a stream of a CO2-rich medium (5), and regeneration of said medium with recovery of CO2 absorbed therein, wherein said raw synthesis gas (102) is produced by the reforming step at a pressure of at least 45 bar, said regeneration of the CO2-loaded medium includes a step of chemical regeneration and the CO2-loaded medium has a temperature of at least 150° C. during said chemical regeneration.

What is claimed is: 
     
       1. A process for making a hydrogen-containing synthesis gas from a hydrocarbon feedstock, comprising the reforming of said hydrocarbon feedstock into a raw synthesis gas and purification of said raw synthesis gas,
 said purification comprising shift conversion of carbon monoxide into carbon dioxide and carbon dioxide removal, 
 said removal of carbon dioxide from the synthesis gas including absorption of carbon dioxide into an absorbing medium, resulting in a stream of a CO2-loaded medium, and regeneration of said medium with recovery of CO2 absorbed therein, 
 wherein: 
 said raw synthesis gas is produced by said reforming step at a pressure of at least 45 bar, 
 said regeneration of the CO2-loaded medium includes a step of chemical regeneration wherein the CO2-loaded medium receives a heat input from a heat source, 
 the CO2-loaded medium, during said chemical regeneration process, has a temperature of at least 160° C., 
 wherein said heat source comprises at least one of the following: 
 an effluent of a shift converter; 
 a feed stream of a shift converter; and 
 a cooling medium which circulates in an isothermal shift converter; 
 wherein said heat source for regeneration of the CO2-loaded medium is a heat source stream having a dew point of at least 190° C. 
 
     
     
       2. The process according to  claim 1 , wherein the steam-to-carbon ratio in the reforming of said hydrocarbon feedstock is 2.9 or greater. 
     
     
       3. The process according to  claim 2 , wherein the steam-to-carbon ratio in the reforming of said hydrocarbon feedstock is 3.3 or greater. 
     
     
       4. The process according to  claim 1 , wherein the regeneration of CO2-loaded medium comprises:
 a first stage of flashing of the CO2-loaded medium from an input pressure to a predetermined flashing pressure, which results in a first amount of physically released carbon dioxide and a semi-lean medium; 
 a second stage of heat stripping of at least a portion of said semi-lean medium, which includes transferring said heat input to the medium, and results in the production of a second amount of chemically released carbon dioxide and a lean medium, said stage of heat stripping being carried out at a stripping pressure; 
 the second amount of carbon dioxide being at least 40% of the total amount of carbon dioxide. 
 
     
     
       5. The process according to  claim 4 , said stripping pressure of the semi-lean medium being at least 3 bar or higher. 
     
     
       6. The process according to  claim 5 , said stripping pressure being at least 5 bar or higher. 
     
     
       7. The process according to  claim 6 , said stripping pressure being in the range 5 to 10 bar. 
     
     
       8. The process according to  claim 4 , said second amount of carbon dioxide being greater than said first amount of carbon dioxide. 
     
     
       9. The process according to  claim 4 , wherein the flashing pressure, to which the CO2-rich medium is flashed and the semi-lean medium is obtained, is greater than or equal to said stripping pressure. 
     
     
       10. The process according to  claim 1 , wherein the absorbing medium is an aqueous solution. 
     
     
       11. The process according to  claim 10 , wherein the absorbing medium is an amine solution. 
     
     
       12. The process according to  claim 1 , said shift converter being a low-temperature shift converter or a medium-temperature shift converter. 
     
     
       13. The process according to  claim 1 , wherein the reforming of the hydrocarbon feedstock into said raw synthesis includes steam reforming and secondary reforming, or auto-thermal reforming. 
     
     
       14. The process according to  claim 1 , wherein the hydrogen-containing synthesis gas is suitable for synthesis of ammonia. 
     
     
       15. The process according to  claim 1 , wherein at least part of the recovered CO2 is compressed for sequestration or for a further use.